Routine Identification of Candida albicans: Current Methods and a New Medium

Abstract

Roughly 1/3 of strains of C. albicans isolated from oral thrush, the feces, and skin lesions of newborn infants, though typical as regards morphology in the lesions and fermentation reactions, consistently failed to form chlamydospores and mycelium on rice infusion agar. Various media recommended for gross and microscopic identification of C. albicans were studied in an attempt to identify 19 such "recalcitrant" strains. The best results were obtained on a medium prepared from an infusion of 10 g "cream of rice" in 1000 ml tap water, agar 10 g, and Tween 80 10 ml. Of the "recalcitrant" strains, 100% tested on this medium formed chlamydospores and abundant mycelium within 24-96 hours. Six non-pathogenic spp. of Candida formed mycelium only. Possible factors influencing chlamydospore formation by C. albicans beside low O2 tension, poly-saccharide media and temperatures below 25[degree]C are discussed.